Electrostatic clamps or chucks (ESCs) are often utilized in the semiconductor industry for clamping workpieces or substrates during plasma-based or vacuum-based semiconductor processes such as ion implantation, etching, chemical vapor deposition (CVD), etc. Clamping capabilities of the ESCs, as well as workpiece temperature control, have proven to be quite valuable in processing semiconductor substrates or wafers, such as silicon wafers. A typical ESC, for example, comprises a dielectric layer positioned over a conductive electrode, wherein the semiconductor wafer is placed on a surface of the ESC (e.g., the wafer is placed on a surface of the dielectric layer). During semiconductor processing (e.g., ion implantation), a clamping voltage is typically applied between the wafer and the electrode, wherein the wafer is clamped against the chuck surface by electrostatic forces.
During workpiece handling and/or processing of workpieces, it is often necessary to verify and/or ensure adequate clamping of the workpiece to the ESC. Furthermore, For certain processes, such as certain ion implantation processes, cooling the workpiece via a cooling of the ESC is desirable, wherein a clamping force between the workpiece and the ESC ensures adequate cooling of the workpiece. Consequently, various configurations for verifying workpiece clamping status have been instituted. One common workpiece verification is based on a change in capacitance associated with the workpiece and ESC, wherein a proximity of the workpiece to the ESC surface generally defines a capacitance between the workpiece and ESC surface. However, such a measured capacitance does not always indicate whether the workpiece is adequately gripped or clamped to the ESC.
Therefore, a need exists in the art for an apparatus, system, and method for determining whether a workpiece is adequately gripped or clamped to a surface of an ESC.